I remember back in the day when a sprinter spun or stopped on the track the car needed to be "backed off" before re-firing. I was always told that was to puke out any raw fuel in the cylinders so as to not hydraulic the motor and bend a valve...Now you never see them backing off, they just straighten out the car and re-fire....What changed to eliminate the need to "back off" the cars?
Also if a car spins, is the driveline still "live" and does it cause the crank to go from forward to reverse (ouch)...seems that would be really tough on cranks to reverse direction in an instant....

From my side of it I haven't had to back off a car in a while. It usually depends on how they spun. Most of the time the car is already off the throttle so the engine isn't loaded up too bad to fire back off. I've had plenty of times where the car is highly loaded up and I can feel it pushing them back off as the car will pop and false fire. As far as still in gear almost every time. Depending on how the car is sitting and what track I'm at will depend on if I even have to get the car in neutral and reposition the the car to push back off. I can't speak for the drivers but from our side of it a good knowledge of what to listen and watch for can make the difference. Our goal is to always have the driver and car as priority one.